The present invention relates to a method and apparatus for manufacturing annular, tubular, cylindrical, and belt-like films used as a conveyor belt for conveying precision parts to a predetermined position with high positional accuracy, and a closed package for packaging or containing goods.
The present invention is principally used as functional parts of an image forming apparatus.
A conventional tubular film manufacturing method and apparatus for forming a sheet film into a tubular film use a heating furnace as a film heating means as proposed in Japanese Patent Laid-Open No. 8-187773.
In this prior art, however, a cylindrical member on which a sheet film is wound and a tubular mold member are placed in a heating furnace held at a certain predetermined temperature. Therefore, the heat is conducted from the tubular mold member as an outer member, so it takes a long time for the film and the cylindrical member to reach the temperature necessary for molding.
Also, since the heat is conducted from the tubular mold member as an outer member, this tubular mold member expands first by the heat to increase the gap with respect to the film wound on the cylindrical member. This makes the conduction of heat to the film and the cylindrical member more and more difficult. Consequently, it takes a long time to reach the necessary molding temperature.
Additionally, in the technique disclosed in Japanese Patent Laid-Open No. 8-187773, the tubular mold member and the cylindrical member used in heat-molding have straight shapes.
FIG. 19 shows the shapes of the conventional tubular mold member and cylindrical member. A sheet film 1006 is wound on a cylindrical member 1002 having a constant outside diameter. This sheet film 1006 wound on the cylindrical member 1002 is inserted into a tubular mold member 1004 and molded by heating. After that, the film formed into the shape of a tube is peeled from the tubular mold member 1004 and cut into a predetermined size to complete a tubular film.
In this prior art, however, the workability of the operation of winding the sheet film on the cylindrical member is low, and this operation cannot be easily automated.
Also, when the tubular film is peeled from the tubular mold member after the heat-molding step, the workability is very low because the tubular film is sticking to the inner surface of the tubular mold member and there is no portion to start peeling. This operation is also difficult to automate.
Ribs can be formed on the inner circumferential surface at the two end portions of the tubular film to prevent meandering of the film when the film is incorporated into a product. When this is the case, ribs must be adhered in a post-process.
Conventionally, to cut a tubular film an operator cuts the two ends of the film by using a cutter or the like.
Also, a method disclosed in Japanese Patent Laid-Open No. 5-307291 is known as a method of extending wrinkles of a film.
In these prior art references, however, it is difficult to cut the end portions of a tubular film perpendicularly to the edge line of the film. Also, a tubular film is creased when cut. Furthermore, since wrinkles produced on a tubular film when the film is cut cannot be removed, the end portions of the film cannot be linearly cut.
No effective means has been proposed which extends wrinkles of a tubular film with high workability or without complicating the apparatus.
Conventionally, when a tubular film is manufactured by winding a sheet film on a cylindrical member, as shown in FIG. 36, the end portion of a sheet film 1006 is temporarily fastened by adhesive tapes 1008 or the like so as to prevent displacement from the outer circumferential surface of a cylindrical member 1002. If the end portion of the sheet film is not fixed to the cylindrical member, the sheet film is loosely wound to produce winding displacement or wrinkles. Consequently, no tubular film having a desired thickness can be obtained after molding.
Also, as disclosed in Japanese Patent Laid-Open No. 10-16093, a suction portion can be formed over the entire width on the outer circumferential surface of a cylindrical member on which a sheet film is wound.
In the former prior art, however, when the adhesive tapes are peeled after the sheet film is wound on the cylindrical member, the sheet film sometimes breaks, and the operation of peeling is troublesome. This makes the operation difficult to automate.
The method disclosed in Japanese Patent Laid-Open No. 10-16093 has the following problem. The sheet film wound on the cylindrical member is inserted into a tubular mold member in the subsequent step and molded into a tubular film by heating. However, since suction holes are formed over the entire width in the outer circumferential surface of the cylindrical member, portions of the film on these suction holes enter the holes during heat-molding. This forms projections as functional defects in the product.
The present invention, therefore, has been made in consideration of the above situation, and has as its object to provide a manufacturing method and apparatus capable of obtaining a high-accuracy tubular film at low cost by performing molding within a short time period.
It is another object of the present invention to provide a manufacturing method and apparatus capable of obtaining a high-accuracy tubular film at low cost by automatization.
It is still another object of the present invention to provide a cutting apparatus having good workability and capable of accurately cutting end portions of a tubular film at low cost.
It is still another object of the present invention to provide a manufacturing method and apparatus capable of obtaining a high-accuracy tubular film at low cost by automatizing winding of a sheet film.
To solve the above conventional problems and achieve the objects, a tubular film manufacturing method according to the present invention is a tubular film manufacturing method of winding a thermoplastic sheet film on a cylindrical member, fitting a tubular mold member on the outside of the wound film, and heating the film together with the cylindrical member and the tubular mold member, thereby molding the sheet film into a tubular film, characterized in that heating means is placed in a central portion of the cylindrical member to heat the cylindrical member from the central portion and join winding start and end portions of the film.
A tubular film manufacturing apparatus of the present invention is a tubular film manufacturing apparatus for winding a thermoplastic sheet film on a cylindrical member, fitting a tubular mold member on the outside of the wound film, and heating the film together with the cylindrical member and the tubular mold member, thereby molding the sheet film into a tubular film, characterized in that heating means is placed in a central portion of the cylindrical member to heat the cylindrical member from the central portion and join winding start and end portions of the film.
A tubular film manufacturing method according to the present invention is a tubular film manufacturing method of winding a thermoplastic sheet film on a cylindrical member, fitting a tubular mold member on the outside of the wound film, and heating the film together with the cylindrical member and the tubular mold member, thereby molding the sheet film into a tubular film, characterized in that the outer diameter at two end portions of the cylindrical member is made smaller than the outer diameter at a central portion thereof, and the length in an axial direction of the central large-diameter portion is made shorter than the width of the sheet film.
A tubular film cutting apparatus according to the present invention is a tubular film cutting apparatus for cutting two end portions of a tubular film, characterized by comprising a rotatable support member for supporting an inner-diameter portion of the tubular film, a driving source for rotating the support member, a first roller capable of contacting the support member, a second roller disposed downstream of the first roller along a rotating direction of the support member, and a cutting blade capable of moving back and forth with respect to the tubular film mounted on the support member.
A tubular film manufacturing method according to the present invention is a tubular film manufacturing method of winding a thermoplastic sheet film on a cylindrical member, fitting a tubular mold member on the outside of the wound film, and heating the film together with the cylindrical member and the tubular mold member, thereby molding the sheet film into a tubular film, characterized in that the sheet film has a width larger than a functionally necessary length of the tubular film, and a winding start portion of the sheet film is held by suction holes formed in an outer circumferential surface at two end portions of the cylindrical member.
A tubular film manufacturing apparatus according to the present invention is a tubular film manufacturing apparatus for winding a thermoplastic sheet film on a cylindrical member, fitting a tubular mold member on the outside of the wound film, and heating the film together with the cylindrical member and the tubular mold member, thereby molding the sheet film into a tubular film, characterized in that the sheet film has a width larger than a functionally necessary length of the tubular film, and suction holes for holding a winding start portion of the sheet film are formed in an outer circumferential surface at two end portions of the cylindrical member.
A tubular film according to the present invention is characterized in that a sheet film member is wound on a cylindrical member and loaded into a tubular member with two ends of the sheet film member overlapped, and the wound sheet film is heated while being rotated together with the tubular member, thereby welding the two overlapped end portions and molding the sheet film into a tubular film.
A tubular film according to the present invention is characterized in that a sheet film is wound on a cylindrical member and loaded into a tubular member with two ends of the sheet film member overlapped, open ends of the wound film member are narrowed, and the wound film member is heated to weld the overlapped portions, thereby molding the film member into a tubular film and the narrowed end portions into ribs.
A tubular film according to the present invention is characterized in that a film member is wound on a cylindrical member having an inclined portion in at least one end portion thereof such that two end portions of the film member overlap each other, the wound film member is loaded into a tubular member and heated to weld the overlapped portions with an end portion of the wound film aligned with the inclined portion of the cylindrical member, thereby molding the wound film member into a tubular film and the inclined portion of the film into a rib.
A tubular film manufacturing apparatus according to the present invention is characterized by comprising a cylindrical member having an inclined portion in at least one end portion, a tubular member for loading the cylindrical member having a sheet film wound on it, the tubular member having an inclined portion corresponding to the inclined portion of the cylindrical member, and heating means for heat-welding the film, wherein the inclined portion of the cylindrical member can be divided.
A tubular film manufacturing apparatus according to the present invention is characterized by comprising a cylindrical member having a stepped portion in at least one end portion, a tubular member for loading the cylindrical member having a sheet film wound on it, the tubular member having a stepped portion corresponding to the stepped portion of the cylindrical member, and heating means for heat-welding the film, wherein the stepped portion of the cylindrical member can be divided.
A tubular film according to the present invention is characterized in that end portions of a sheet film are joined to form a tubular film, and end portions of the tubular film are cut while the tubular film is rotated.
A tubular film cutting method according to the present invention is characterized in that a tubular film is fitted on a rotary member and rotated, a portion of the film is extended on the surface of the rotary member, and the extended portion of the film is cut by a cutting blade.
A tubular film cutting apparatus according to the present invention is a tubular film cutting apparatus characterized by comprising a rotary member for fitting a tubular film on it, pressing means for pressing the tubular film against the rotary member, and cutting means for cutting the tubular film pressed against the rotary member by the pressing means.
A tubular film manufacturing method according to the present invention is a tubular film manufacturing method of winding a sheet film on a cylindrical member, loading the sheet film into a tubular member, and heating the sheet film to form a tubular film, characterized in that the sheet film is wound on the cylindrical member by holding an end portion of the sheet film to the cylindrical member by suction.
A fitting method according to the present invention is a method of winding a sheet film on a cylindrical member and fitting a tubular member on the outside of the cylindrical member having the film wound on it, characterized in that the tubular member is fitted on the cylindrical member while a winding end portion of the film is pressed by an elastically deformable press member which deforms in accordance with the shape of an end portion of the tubular member.